U.S. patent number 4,934,096 [Application Number 07/248,040] was granted by the patent office on 1990-06-19 for apparatus for automatically watering plants.
This patent grant is currently assigned to Innocom (Electro) B.V.. Invention is credited to Gerardus J. Bentvelsen.
United States Patent |
4,934,096 |
Bentvelsen |
June 19, 1990 |
Apparatus for automatically watering plants
Abstract
Apparatus for automatically watering plants, comprising a fluid
tight reservoir containing a substrate onto which the plants are
positioned, means to apply fluid to said plants and means to
receive the not directly absorbed fluid and conduct said fluid to a
measuring reservoir. Analog level detectors are used to generate
level proportional signals to a processor in which these signals
are compared with reference signals to generate control signals to
said means for applying fluid.
Inventors: |
Bentvelsen; Gerardus J.
(Maassluis, NL) |
Assignee: |
Innocom (Electro) B.V.
(Gravenzande, NL)
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Family
ID: |
19850663 |
Appl.
No.: |
07/248,040 |
Filed: |
September 23, 1988 |
Foreign Application Priority Data
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Sep 24, 1987 [NL] |
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8702286 |
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Current U.S.
Class: |
47/62N;
47/79 |
Current CPC
Class: |
A01G
27/003 (20130101) |
Current International
Class: |
A01G
27/00 (20060101); A01G 031/00 () |
Field of
Search: |
;47/59,62,79,30 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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322264 |
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Jan 1975 |
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AT |
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0142989 |
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Nov 1985 |
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EP |
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2813410 |
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Apr 1979 |
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DE |
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WO8600494 |
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Apr 1986 |
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WO |
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Primary Examiner: Raduazo; Henry E.
Attorney, Agent or Firm: Bachman & LaPointe
Claims
I claim:
1. Apparatus for automatically watering plants, comprising:
a fluid tight reservoir containing a substrate on which plants are
positioned;
a gutter running underneath said reservoir in open communication
with a bottom of said reservoir;
a fluid absorbing matting installed within said gutter and at least
on a part of the bottom of the reservoir;
a measuring reservoir in open communication with said gutter;
level metering means installed within said measuring reservoir;
a conduit system, connected through a pump to a fluid source;
said conduit system including a fluid dispensing orifice for each
of said plants;
a processor which receives signals from said level measuring means
and supplied control signals to said pump;
said level measuring means being an analog level measuring means
for generating a signal to be delivered to said processor
proportional to a fluid level in said measuring reservoir;
adjustment means for supplying at least one reference signal for
determining a maximum level and a minimum level, to said processor;
and
the processor comparing at least one of an output signal of the
level measuring means and a signal derived therefrom with said at
least one reference signal to start the operation of the pump in a
first case where one predetermined signal combination is detected
and to stop the functioning of the pump in a second case whee
another predetermined signal combination is detected.
2. Apparatus according to claim 1, further characterized in that
the processor generates an output signal related to a derivative of
the level measuring means signal, said output signal being used for
controlling systems for influencing the environmental climate.
3. Apparatus according to claim 1, characterized in that the
processor generates an output signal related to a derivative of the
level measuring means signal, said output signal during operation
of the apparatus being supplied to a further processor programmed
to control systems for influencing the environmental climate.
4. Apparatus according to claim 3, characterized in that both
processors are combined in a single programmed computer.
5. Apparatus according to claim 1, characterized in that the
processor comprises means for determining the derivative of the
level measuring means signal and a velocity with which the fluid
level in the measuring reservoir changes; and said processor being
used to control the opeation of the pump therewith.
6. Apparatus according to claim 2, characterized in that the
processor compares the level measuring means signal with the at
least one reference signal to switch off the pump when the maximum
level is reached and to switch on the pump when the minimum level
is reached.
7. Apparatus according to claim 1, characterized in that the
processor is coupled to a display means on which variations in the
level measuring means signal and therewith variations of the fluid
level in the measuring reservoir as function of time can be
visualised.
8. Apparatus according to claim 1, characterized in that the
measuring reservoir comprises a discharge channel containing a
processor controlled valve, said valve being opened or closed by
the processor when predetermined levels are reached.
9. Apparatus according to claim 8, characterized in that said
apparatus being operational in an overdrain mode during which the
maximum level signal is neglected for a predetermined time period
so that the level in the measuring reservoir rises to a
predetermined level at which the valve opens causing the discharge
of fluid, said valve remaining open until it is closed at another
further level, said opening and closing of the valve being repeated
a number of times until the overdrain mode is ended, whereby the
processor calculates an amount of drained fluid based on variations
in the level measuring means signal as a function of time.
Description
The invention relates to an apparatus for automatically watering
plants, comprising:
a fluid tight reservoir containing a substrate onto which the
plants are positioned;
a gutter running underneath said reservoir in open communication
with the bottom of said reservoir, whereby within said gutter and
at least on a part of the bottom of the reservoir a fluid absorbing
matting is installed;
a measuring reservoir in open communication with said gutter;
level measuring means installed within said measuring
reservoir;
a conduit system, connected through a pump to a fluid reservoir and
comprising a fluid dispensing orifice for each of said plants;
a processor receiving signals from said level measuring means and
supplying control signals to said pump.
Such an apparatus is known from the Dutch patent application
83.03579. In this prior art apparatus, the level measuring means
are embodied as level probes in the form of rods or stripes, made
of electrically conducting material and mounted into the measuring
reservoir by means of mechanical clamping elements such that the
lower ends thereof are positioned at the maximum and minimum level
respectively. These level probes are connected through suitable
wires to the processor which in this case may consist of a number
of simple detection circuits for determining if the probes are
earthed through the liquid or not. If the fluid level descends
underneath the minimum level then the contact between the minimum
level probe and the fluid is interrupted, which interruption is
detected in the processor in response whereto a signal is generated
for activating the pump. By means of the pump watering fluid is
pumped into the conduit system and is delivered drop by drop to
each of the plants through said fluid dispensing orifices. Because
the fluid is supplied to the plants significantly faster than it is
absorbed by the plants the level in the measuring reservoir will
rise. As soon as the lower end of the maximum level probe comes
into contact with the fluid in the measuring reservoir the
processor generates a signal to switch off the pump. This process
is repeated in a sequential order.
The use of mechanically adjustable level probes has the
disadvantage that, in case the plant grower for one reason or
another finds it desirable to adjust one or both levels to another
position, then he has to manipulate the mechanical clamping means
which is experienced as rather difficult. Furthermore because of
said mechanical adjustment an accurate level setting with these
type of probes is hardly possible as practice has proved.
Furthermore with this prior art apparatus no insight information is
obtained about the way in which the plants do respond to the
watering. The desired maximum and minimum levels for certain plants
have to be adjusted by the grower on the basis of his experience
and on the basis of his personal observation of the growth
behaviour of the plants.
An object of the invention is now to embody the apparatus,
mentioned in the first paragraph of this specification such that
the level adjustment will be significantly simplified so that the
ease of operation of the apparatus for the grower will be enhanced.
Furthermore a better understanding will be obtained in the
functioning of the apparatus, in the way in which the plants
respond to the behaviour of the apparatus and in the influence of
the environmental conditions on the water evaporation of the
plant.
According to the invention the apparatus of the type, mentioned in
the heading paragraph is characterized in that:
the level measuring means are embodied as analog level measuring
means generating a signal to be delivered to said processor
proportional to the fluid level in said measuring reservoir;
adjustment means are present for supplying at least reference
signals, determining the maximum level and the minimum level, to
said processor; and
the processor compares the output signal of the level measuring
means or a signal derived therefrom with the reference signals to
start the operation of the pump in case one predetermined signal
combination is detected and to stop the functioning of the pump in
case another predetermined signal combination is detected.
By using analog measuring means delivering an analog signal and by
a suitable processing of this analog signal, a better understanding
can be obtained about the evaporation of the plants, which for a
grower is often a vital piece of information. In this respect a
preferred embodiment of the apparatus according to the invention is
characterized in that the processor generates an output signal,
related to the derivative of the level measuring means signal,
which output signal can be used for controlling systems for
influencing the environmental climate, such as systems for heating,
ventilation, illumination, CO.sub.2 -dosing, sunlight- or energy
screening, air humidity control.
In general, the level measuring means signal as well as the
derivative thereof can be used in a suitably programmed computer to
generate, on the basis thereof, control signals for controlling the
functioning of various types of climate control devices.
A further embodiment is characterized in that the processor
comprises means of software to determine the derivative of the
level measuring means signal and therewith the velocity with which
the fluid level in the measuring reservoir changes, to control the
operation of the pump therewith.
Based on the determined velocity, conclusions can be drawn about
the evaporation of the plant. On the basis of the measured
velocity, start- and stop signals for the pump can be generated. In
such an embodiment, the evaporation velocity is therefor the major
criterium for the pump control and not the actual level of the
measuring reservoir.
The above-mentioned adjustment means may for instance comprise
accurately adjustable potentiometers, thumb wheel switches, a
digital keyboard etc., by means of which on the one hand in a very
user friendly way and on the other hand also in a very accurate way
signals, related to the minimum level and to the maximum level, can
be delivered to the processor. Compared with the prior art
apparatus the ease of operation and the comfort for the grower is
enhanced significantly. Furthermore, thanks to the very simple
operation a significant time saving is obtained.
Further advantage of the apparatus according to the invention
follows from the fact that the variation of the level in the
measuring reservoir is in fact registered continuously by the
analog level measuring means. If the level variations are
visualised as functions of time, than the grower is able to derive
therefrom directly very interesting and very useful data. Therefore
a preferred embodiment of the apparatus according to the invention
is characterized in that the processor is coupled to display means
onto which the variation of the level measuring means signal and
therewith the variation of the fluid level in the measuring
reservoir as function of time can be made visualized. Especially
the angle of the slopes in the signal curve as the signal varies
between a maximum and a minimum or vice versa provides important
information about the velocity with which the fluid is absorbed by
the plant or evaporated thereby and may eventually lead to further
measures taken by the grower.
In this respect a preferred embodiment of the invention is
characterized in that the measuring reservoir comprises a discharge
channel containing a processor controlled valve, which valve is
opened or closed by the processor when predetermined levels are
reached.
After a lapse of time, a deposit of salts will be formed in the
matting which should be removed during a so-called overdrain
procedure known to the expert in this field. In this respect, a
specific embodiment of the apparatus according to the invention is
characterized in that the apparatus can be used in an overdrain
mode in which, during a predetermined time period, the maximum
level signal is neglected so that the level in the measuring
reservoir rises to a predetermined further level at which the
discharge valve is opened, causing the discharge of fluid until at
another further level the discharge valve is closed. The opening
and closing of the discharge valve can be repeated a number of
times until the overdrain mode is ended, whereby the processor or
computer is suitable programmed for calculating the amount of
drained fluid based on the variations in the level measuring means
signal as a function of time.
The invention will be explained in more detail with reference to
the attached drawings.
FIG. 1 shows schematically a general view of the main components of
the apparatus according to the invention.
FIG. 2 illustrates a cross sectional view through the reservoir and
through the gutter forming part of the apparatus according to the
invention.
FIG. 3 illustrates an example of the way in which the level
measuring means signal varies.
FIG. 4 illustrates in a diagram the relation between the sunlight
radiation and the water level.
FIG. 5 provides more details about the analog level measuring
means.
FIG. 6 illustrates a multiplex configuration, in which a number of
apparatusses according to the invention are combined with one
single processor.
In FIG. 1 an embodiment of the apparatus according to the invention
is shown in a more detailed manner. The apparatus comprises a fluid
tight reservoir 1 with therein a substrate 2 onto which the plants
(in this example three plants are indicated by 3, 4 and 5) are
positioned each in a separate pot, respectively indicated by 6, 7
and 8. The growing of plants on a substrate is a technology which
is considered as known to the expert in this field and will not be
discussed in detail. As appears furthermore from FIG. 2, in which a
cross-sectional view through the reservoir 1 is illustrated, a
gutter 10 is installed underneath the reservoir 1 such, that the
there is an open communication path between a slot in the bottom of
the reservoir 1 to which the gutter 10 closely fits and the gutter
itself. Within the gutter and onto the bottom wall of the reservoir
1 a matting consisting of fluid absorbing material of a material
with capillary action, is installed. This material is indicated by
the reference number 11.
At one end of the gutter a measuring reservoir 12 is installed
having an open communication connection with the gutter as appears
from FIG. 1. In this measuring reservoir, an analog level probe 13
is positioned. Through a suitable conduit 14, the probe 13 is
connected to the level measuring unit 15. The measuring unit 15
supplies output signals to the computer 22 which in this example
execute the function of the processor. In the usual manner the
computer 22 comprises a display screen 16 and a keyboard 17 as well
as a central processing unit.
At the lower end of the measuring reservoir 12, a discharge pipe 18
is connected in which a remotely controllable valve 19 is
installed. The valve 19 can be operated through line 23 by means of
a signal generated by the computer 22. Furthermore a separate alarm
probe 20 is positioned in the measuring reservoir and connected
through a suitable line 21 to the computer 22. This alarm probe
only delivers a signal in case the fluid level in the measuring
reservoir descends underneath an abnormal low value.
As shown in FIG. 1, the apparatus further includes a conduit system
33, connected through a pump 31 to a fluid source 32. The conduit
system further includes a fluid dispensing orifice 34A, 34B, and
34C for each plant 3, 4 and 5.
The operation of the circuit illustrated in the FIGS. 1 and 2 will
be discussed in more detail with reference to FIG. 3. In FIG. 3,
the variation of the output signal of the analog level probe 13
over a period of 24 hours as function of the time is shown. Along
the vertical axis the water level is indicated in percentages. The
0% level as well as the 100% level in the measuring reservoir can
be selected in an arbitrary way as will be discussed hereinafter.
As appears from FIG. 3, the pump 31 was switched on in the morning
at .+-.7.00 hours and water was supplied until the maximum level
was reached. It is remarked that during the night all fluid was
absorbed from the substrate and from the absorbing matter or was
evaporated and that the level in the measuring reservoir was
lowered until 0%. After reaching the maximum level, in this case
adjusted to 70%, the pump 31 was stopped and the supply of water
was at least for the time being ended. The plants require, as
appears from the first rather broad peak in the diagram, apparently
some time to adapt themselves to the new situation, however,
thereafter they start absorbing the water resulting into a gradual
lowering of the water level until 55%, corresponding to the
adjusted minimum level. After reaching this minimum level the pump
31 is reactivated and again drop by drop fluid is added until the
water level again reaches the maximum of 70%. Directly after the
reactivation of the pump 31 the ascending fluid flow in the
aborbing material 11 will have to be compensated before the level
in the measuring reservoir will rise again. This appears also from
the short horizontal sections in he curve of FIG. 3. This cyclic
process is continued during the day until at .+-.18.00 hours the
last fluid drops are delivered whereafter the level is allowed to
descend even underneath the minimum level to create therewith a
favourable situation for the night.
As appears from FIG. 3 the velocity with which the fluid evaporates
respectively is absorbed by the plant during the morning increases
whereafter the velocity obtains a rather stable character. The
computer 22 is preferably programmed such, that from the input
signal, received from the level probe 13, the slope is determined
between its maximum and its minimum (70%, respectively 55%), which
slope is directly related to the velocity with which the water
level in the measuring reservoir varies. Furthermore, the computer
can be programmed such that with a velocity which is too high or
too low (to be determined separately for ascending and descending
parts of the curve an alarm signal is generated. The velocity
differences may be caused (at least partly by climatological
changes during the day). One of the factors playing a role thereby
is the sunlight radiation. As appears from FIG. 4 an increasing
sunlight radiation results into an increasing evaporation which
becomes evident from a faster descending level curve between a
maximum and the adjacent minimum. Based on the momentary slope
angle, which can be determined for instance by the computer 22, the
grower is now able to take decisions about opening or closing
windows, lowering or rising the temperature and if necessary
adapting the humidity. This slope angle can be made visible on the
screen of the computer; however, it is also possible to directly
generate a control signal for instance to a mechanism for
controlling the windows or to a climate control device in which
this signal is processed as one of an eventual larger number of
detection signals.
In FIG. 4 the slope angle of the curve is measured continuously.
The slope indicated by b caused by the peak a in the sunlight
radiation, initiated the computer to activate the pump 31 already
before the minimum level was obtained.
Above the attention is drawn to the fact that the apparatus
according to the invention uses an analog level measuring device.
Although one could think of a simple floating body coupled to a
position-voltage-converter such as a potentiometer or a similar
device, it is preferred to use an embodiment without any moving
parts. A possible embodiment is schematically illustrated in FIG.
5. In this figure a cross-section is shown through a part of the
reservoir 1 with the gutter 10 and the thereto connected measuring
reservoir 12. Furthermore in this figure the discharge valve 19 and
the discharge channel 18 are illustrated. In the measuring
reservoir a pipe 30 is installed, the upper end of which in an air
tight manner connected to an air conduit 21. The other end of this
air conduit is air tight connected to a pressure sensitive sensor
24. Such sensors are commercially available in various embodiments
and do not require any explanation. Through the electrical wiring
25 the output signal of the sensor 24 is supplied to a level
measuring circuit (15 in FIG. 1) with which the output signal of
the sensor 24 is converted into a signal suitable for reception by
the computer 22.
The 0% level in this embodiment is selected arbitrarily by the
lower end of the pipe 30, which lower end is furthermore positioned
underneath the lowest level of the gutter 10, so that the analog
level detector can be calibrated easily. If fluid is poured into
the initially empty measuring reservoir then the output signal of
the pressure sensor will not show any change until the moment the
0% level is reached. At that moment the volume of air within the
pipe 30 and within the conduit 21 is closed by the fluid and each
further rise of the fluid level in the actual measuring reservoir
will result into a pressure increase in this closed volume of air
resulting into a thereto corresponding output signal of the
pressure sensor 22. The 100% level can be calibrated once very
simply for instance at the level of the bottom of the reservoir 1.
The output signal of the pressure sensor, corresponding to this
level, is assigned to the 100% level and the intermediate variation
of the signal can be stored into the memory of the computer as a
calibration curve. Therewith the apparatus is ready for use.
By means of the keyboard the grower is able to input very simply
percentage values for a selected minimum and maximum level into the
computer. During operation in the computer continuously the output
signal of the pressure sensor 22 is compared to these maximum and
minimum values and if one of these limit levels is reached the pump
is switched on or is switched off.
If for one reason or another the level in the measuring reservoir
would descend until the alarm probe 20 becomes free, then the
resulting signal therefrom is processed by the computer into a
suitable alarm signal. If on the other hand for one reason or
another the level in the measuring reservoir would ascend above a
predetermined limit value, for instance 75% in FIG. 3, then the
computer has the ability to open a valve 19 until a predetermined
lower level is reached at which level the valve 19 is closed
again.
In a plant growing firm in general a number of such apparatusses
will be used alongside each other, either for the same type of
plants or for different type of plants per apparatus. It is not
necessary to duplicate the whole system each time. The computer can
be used in multiplex configuration for controlling a large number
of such apparatusses.
FIG. 6 illustrates an example of a system comprising two units as
schematically indicated in FIG. 1, connected through a multiplexer
to a central computer. Each of the separate units has two output
lines and one input line, more specifically an output line 21a, 21b
for the alarm probe, an output line 27a, 27b for the level
detection circuit and an input line 23a, 23b for controlling the
discharge valve 19. Between the computer 22 and the multiplexer 26
corresponding lines 21c, 27c and 23c are installed. The function of
the multiplexer 26 is controlled through a line 28 by the computer.
The functioning of multiplex systems is regarded as within the
knowledge of the expert in this field and will not be discussed in
detail therefore.
It will be clear that such a multiplex system is able to control a
large number of separate apparatusses each with own parameters in a
very comfortable and easy way by the grower. Data of each of these
separate apparatusses can be stored in a memory and, selected by
the user, visualised onto the screen. It will furthermore be clear,
that dependent on the used computer, it is not necessary under all
circumstances to use a separate multiplexer 26. Many computers have
an integrally built in mulplexer function.
* * * * *